Solid electrolyte batteries are based on the principle of solid electrolyte fuel cells, which are enhanced by adding storage elements to the battery. These storage elements conventionally have ceramic base bodies in which particles of a metal and/or a metal oxide, which together form a redox pair, are incorporated. In the charged state of the battery, the particles are in this case reduced to the metal. By electrochemical oxidation with atmospheric oxygen, it is possible to obtain energy which can be drawn as electrical energy at the tapping poles of the battery. Once the metal particles have been fully oxidized to the respective metal oxide, the battery is discharged. In order to recharge the battery, the fuel cell is then operated in electrolysis mode, hydrogen which reduces the metal oxides back to the metal being formed.
In the manufacture of such batteries, the problem arises of exploiting the theoretically existing storage capacity of the storage elements as effectively as possible, and of permitting a discharging characteristic in potentiometric or galvanostatic operation which is as constant as possible. It is furthermore of great importance to ensure longterm stability both under charging/discharging cycles and in standby operation.
Of great importance in this case is the accessibility of the active metal species in the storage element for the redox reaction, which in particular influences the degree of utilization and the reaction kinetics of the charging and discharging process, as well as the susceptibility to degradation.
Hitherto conventional storage elements have an isotropic skeleton-like structure of the ceramic base body with uniformly distributed open, or closed pores. In order to prevent losses of the storage capacity by sintering of the reactive metal particles together, and concomitant reduction of the available active surface area, so-called ODS (oxide dispersion strengthened) metal particles are mostly used nowadays, which are mixed with coarse-grained zirconium dioxide, dry-pressed and slightly sintered.